A sample weight value is a measure of the number of people in the population represented by a specific sample person in NHANES. Sample weights are constructed for each two-year survey cycle to account for over-sampling, survey non-response, and post-stratification. Because not all sampled persons completed all portions of the survey, each individual represented in a public release file may have different sample weights assigned, depending on the nature of the non-response adjustments necessary. When using weights, it is important to select the correct weight variable (i.e. either from the Demographic file or from one of the other data files), namely the variable that applies to all members of the smallest analysis subpopulation.
Depending on the individuals with data for the particular variables you want to use in your dietary analysis, you will need to choose from several different types of sample weights. Sample weights and information about the type to use for a particular dataset are located within the files and documentation of that dataset.
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